This article is largely based on an article in the out-of-copyright Encyclopædia Britannica Eleventh Edition, which was produced in 1911. (February 2023) |
A glucoside is a glycoside that is chemically derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes.
The name was originally given to plant products of this nature, in which the other part of the molecule was, in the greater number of cases, an aromatic aldehydic or phenolic compound (exceptions are Jinigrin and Jalapin or Scammonin). It has now been extended to include synthetic ethers, such as those obtained by acting on alcoholic glucose solutions with hydrochloric acid, and also the polysaccharoses, e.g. cane sugar, which appear to be ethers also. Although glucose is the most common sugar present in glucosides, many are known which yield rhamnose or iso-dulcite; these may be termed pentosides. Much attention has been given to the non-sugar parts (aglycone) of the molecules; the constitutions of many have been determined, and the compounds synthesized; and in some cases the preparation of the synthetic glucoside effected.
The simplest glucosides are the alkyl ethers which have been obtained by reacting hydrochloric acid on alcoholic glucose solutions. A better method of preparation is to dissolve solid anhydrous glucose in methanol containing hydrochloric acid. A mixture of alpha- and beta-methylglucoside results.
The classification of glucosides is a matter of some intricacy. One method based on the chemical constitution of the non-glucose part of the molecules has been proposed that posits four groups: (1) alkyl derivatives, (2) benzene derivatives, (3) styrolene derivatives, and (4) anthracene derivatives. A group may also be constructed to include the cyanogenic glucosides, i.e. those containing prussic acid. Alternate classifications follow a botanical classification, which has several advantages; in particular, plants of allied genera contain similar compounds. This article follows the chemical classification and discusses only the more important compounds.
Ethylene derivatives
These are generally mustard oils, which are characterized by a burning taste; their principal occurrence is in mustard and Tropaeolum seeds. Sinigrin, or the potassium salt of not only occurs in mustard seed, but also in black pepper and in horseradish root. Hydrolysis with barium hydroxide, or decomposition by the ferment myrosin, gives glucose, allyl mustard oil and potassium hydroxide. Sinalbin occurs in white pepper; it decomposes to the mustard oil, glucose and sinapin, a compound of choline and sinapic acid. Jalapin or Scammonin occurs in scammony; it hydrolyses to glucose and .
Benzene derivatives
These are generally oxy and oxyaldehydic compounds.
- Benzoic acid derivatives
The benzoyl derivative has been used for tuberculosis. Populin, which occurs in the leaves and bark of Populus tremula, is benzoyl salicin.Benzoyl-beta-D-glucoside is a compound found in the fern Pteris ensiformis.
- Phenol derivatives
There are a number of glucosides found in natural phenols and polyphenols, as, for example, in the flavonoids chemical family. Arbutin, which occurs in bearberry along with , hydrolyses to hydroquinone and glucose. Pharmacologically it acts as a urinary antiseptic and diuretic; Salicin, also termed Saligenin and glucose occurs in the willow. The enzymes ptyalin and emulsin convert it into glucose and saligenin, ortho-oxybenzylalcohol. Oxidation gives the aldehyde helicin.
Styrene derivatives
This group contains a benzene and also an ethylene group, being derived from styrene. Coniferin (C16H22O8) occurs in the cambium of conifer wood. Emulsin converts it into glucose and coniferyl alcohol. Oxidation of coniferin gives glucovanillin, which yields upon treatment with emulsin glucose and vanillin. Syringin, which occurs in the bark of Syringa vulgaris, is a . Phloridzin occurs in the root-bark of various fruit trees; it hydrolyses to glucose and phloretin, which is the phloroglucin ester of . It is related to the pentosides naringin (C27H32O14), which hydrolyzes to rhamnose and naringenin, the phloroglucin ester of p-coumaric acid, and hesperidin, which hydrolyzes to rhamnose and hesperetin, the phloroglucin ester of isoferulic acid (C10H10O4).
- Aesculin (C21H24O13), occurring in horse-chestnut and California buckeye, and daphnin, occurring in Daphne alpina, are isomeric; the former hydrolyzes to glucose and aesculetin (C9H6O4 — 6,7-dihydroxycoumarin), the latter to glucose and daphnetin (7,8-dihydroxycoumarin).
- Fraxin, occurring in Fraxinus excelsior, hydrolyzes to glucose and fraxetin (also known as 7,8-dihydroxy-6-methoxycoumarin)
- Flavone or benzo-7-pyrone derivatives are numerous; in many cases they (or the non-sugar part of the molecule) are vegetable dyes.
- Rhamnetin, a splitting product of the glucosides of Rhamnus, is monomethyl quercetin; fisetin, from Rhus cotinus, is monoxyquercetin; chrysin is phenyl-dihydroxybenzopyrone.
- Saponarin, a glucoside found in Saponaria officinalis, is a related compound.
- Strophanthin is the name given to two different compounds, g-strophanthin (ouabain) obtained from Strophanthus gratus and k-strophanthin from Stroph. kombé.
Anthracene derivatives
This section needs to be updated. (September 2018) |
These are generally substituted anthraquinones; many have medicinal applications, being used as purgatives, while one, ruberythric acid, yields the valuable dyestuff madder, the base of which is alizarin. Chrysophanic acid, a dioxymethylanthraquinone, occurs in rhubarb, which also contains emodin, a ; this substance occurs in combination with rhamnose in Frangula bark.
Arguably the most important cyanogenic glucoside is amygdalin, which occurs in bitter almonds. The enzyme maltase decomposes it into glucose and ; the latter is broken down by emulsin into glucose, benzaldehyde and prussic acid. Emulsin also decomposes amygdalin directly into these compounds without the intermediate formation of mandelic nitrile glucoside.
Several other glucosides of this nature have been isolated. The saponins are a group of substances characterized by forming a lather with water; they occur in soap-bark. Mention may also be made of indican, the glucoside of the indigo plant; this is hydrolysed by the indigo ferment, , to indoxyl and indiglucin.
References
- Chisholm 1911, p. 142.
- Jen, Jen-Fon; Lina, Tsai-Hung; Huang, Jenn-Wen; Chung, Wen-Chuan (2001). "Direct determination of sinigrin in mustard seed without desulfatation by reversed-phase ion-pair liquid chromatography". Journal of Chromatography A. 912 (2): 363–368. doi:10.1016/S0021-9673(01)00591-X. PMID 11330806.
- Chisholm 1911, pp. 142–142.
- Hogan, C. Michael (2008). Stromberg, N. (ed.). "Aesculus californica". Globaltwitcher.com. Archived from the original on 22 November 2012. Retrieved 22 October 2008.
- Chisholm 1911, p. 143.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Glucoside". Encyclopædia Britannica. Vol. 12 (11th ed.). Cambridge University Press. pp. 142–143.
Further reading
- Brito-Arias, Marco – Synthesis and Characterization of Glycosides editorial Springer 2007
This article is largely based on an article in the out of copyright Encyclopaedia Britannica Eleventh Edition which was produced in 1911 It should be brought up to date to reflect subsequent history or scholarship including the references if any When you have completed the review replace this notice with a simple note on this article s talk page February 2023 A glucoside is a glycoside that is chemically derived from glucose Glucosides are common in plants but rare in animals Glucose is produced when a glucoside is hydrolysed by purely chemical means or decomposed by fermentation or enzymes Chemical structure of decyl glucoside a plant derived glucoside used as a surfactant The name was originally given to plant products of this nature in which the other part of the molecule was in the greater number of cases an aromatic aldehydic or phenolic compound exceptions are Jinigrin and Jalapin or Scammonin It has now been extended to include synthetic ethers such as those obtained by acting on alcoholic glucose solutions with hydrochloric acid and also the polysaccharoses e g cane sugar which appear to be ethers also Although glucose is the most common sugar present in glucosides many are known which yield rhamnose or iso dulcite these may be termed pentosides Much attention has been given to the non sugar parts aglycone of the molecules the constitutions of many have been determined and the compounds synthesized and in some cases the preparation of the synthetic glucoside effected The simplest glucosides are the alkyl ethers which have been obtained by reacting hydrochloric acid on alcoholic glucose solutions A better method of preparation is to dissolve solid anhydrous glucose in methanol containing hydrochloric acid A mixture of alpha and beta methylglucoside results The classification of glucosides is a matter of some intricacy One method based on the chemical constitution of the non glucose part of the molecules has been proposed that posits four groups 1 alkyl derivatives 2 benzene derivatives 3 styrolene derivatives and 4 anthracene derivatives A group may also be constructed to include the cyanogenic glucosides i e those containing prussic acid Alternate classifications follow a botanical classification which has several advantages in particular plants of allied genera contain similar compounds This article follows the chemical classification and discusses only the more important compounds Ethylene derivativesThese are generally mustard oils which are characterized by a burning taste their principal occurrence is in mustard and Tropaeolum seeds Sinigrin or the potassium salt of not only occurs in mustard seed but also in black pepper and in horseradish root Hydrolysis with barium hydroxide or decomposition by the ferment myrosin gives glucose allyl mustard oil and potassium hydroxide Sinalbin occurs in white pepper it decomposes to the mustard oil glucose and sinapin a compound of choline and sinapic acid Jalapin or Scammonin occurs in scammony it hydrolyses to glucose and Benzene derivativesThese are generally oxy and oxyaldehydic compounds Benzoic acid derivatives The benzoyl derivative has been used for tuberculosis Populin which occurs in the leaves and bark of Populus tremula is benzoyl salicin Benzoyl beta D glucoside is a compound found in the fern Pteris ensiformis Phenol derivatives There are a number of glucosides found in natural phenols and polyphenols as for example in the flavonoids chemical family Arbutin which occurs in bearberry along with hydrolyses to hydroquinone and glucose Pharmacologically it acts as a urinary antiseptic and diuretic Salicin also termed Saligenin and glucose occurs in the willow The enzymes ptyalin and emulsin convert it into glucose and saligenin ortho oxybenzylalcohol Oxidation gives the aldehyde helicin Styrene derivativesThis group contains a benzene and also an ethylene group being derived from styrene Coniferin C16H22O8 occurs in the cambium of conifer wood Emulsin converts it into glucose and coniferyl alcohol Oxidation of coniferin gives glucovanillin which yields upon treatment with emulsin glucose and vanillin Syringin which occurs in the bark of Syringa vulgaris is a Phloridzin occurs in the root bark of various fruit trees it hydrolyses to glucose and phloretin which is the phloroglucin ester of It is related to the pentosides naringin C27H32O14 which hydrolyzes to rhamnose and naringenin the phloroglucin ester of p coumaric acid and hesperidin which hydrolyzes to rhamnose and hesperetin the phloroglucin ester of isoferulic acid C10H10O4 Aesculin C21H24O13 occurring in horse chestnut and California buckeye and daphnin occurring in Daphne alpina are isomeric the former hydrolyzes to glucose and aesculetin C9H6O4 6 7 dihydroxycoumarin the latter to glucose and daphnetin 7 8 dihydroxycoumarin Fraxin occurring in Fraxinus excelsior hydrolyzes to glucose and fraxetin also known as 7 8 dihydroxy 6 methoxycoumarin Flavone or benzo 7 pyrone derivatives are numerous in many cases they or the non sugar part of the molecule are vegetable dyes Rhamnetin a splitting product of the glucosides of Rhamnus is monomethyl quercetin fisetin from Rhus cotinus is monoxyquercetin chrysin is phenyl dihydroxybenzopyrone Saponarin a glucoside found in Saponaria officinalis is a related compound Strophanthin is the name given to two different compounds g strophanthin ouabain obtained from Strophanthus gratus and k strophanthin from Stroph kombe Anthracene derivativesThis section needs to be updated Please help update this article to reflect recent events or newly available information September 2018 These are generally substituted anthraquinones many have medicinal applications being used as purgatives while one ruberythric acid yields the valuable dyestuff madder the base of which is alizarin Chrysophanic acid a dioxymethylanthraquinone occurs in rhubarb which also contains emodin a this substance occurs in combination with rhamnose in Frangula bark Arguably the most important cyanogenic glucoside is amygdalin which occurs in bitter almonds The enzyme maltase decomposes it into glucose and the latter is broken down by emulsin into glucose benzaldehyde and prussic acid Emulsin also decomposes amygdalin directly into these compounds without the intermediate formation of mandelic nitrile glucoside Several other glucosides of this nature have been isolated The saponins are a group of substances characterized by forming a lather with water they occur in soap bark Mention may also be made of indican the glucoside of the indigo plant this is hydrolysed by the indigo ferment to indoxyl and indiglucin ReferencesChisholm 1911 p 142 Jen Jen Fon Lina Tsai Hung Huang Jenn Wen Chung Wen Chuan 2001 Direct determination of sinigrin in mustard seed without desulfatation by reversed phase ion pair liquid chromatography Journal of Chromatography A 912 2 363 368 doi 10 1016 S0021 9673 01 00591 X PMID 11330806 Chisholm 1911 pp 142 142 Hogan C Michael 2008 Stromberg N ed Aesculus californica Globaltwitcher com Archived from the original on 22 November 2012 Retrieved 22 October 2008 Chisholm 1911 p 143 This article incorporates text from a publication now in the public domain Chisholm Hugh ed 1911 Glucoside Encyclopaedia Britannica Vol 12 11th ed Cambridge University Press pp 142 143 Further readingBrito Arias Marco Synthesis and Characterization of Glycosides editorial Springer 2007
